This invention relates to construction equipment, and more particularly construction equipment of the type used to form a cementitious material to a desired profile.
In certain construction projects, it is necessary to form a cementitious material such as concrete, gunite or the like to a desired interior profile. Projects of this type include swimming pools or artificial ponds. Additionally, in recent years skateboarding "bowls" have become increasingly popular, and also entail forming gunite to a desired interior profile In an application such as this, it is very important that the surface of the bowl be very smooth and not have any ripples, ridges or the like which interfere with the skateboard ride.
In the past, it has been known to form an interior structure such as a swimming pool, skateboard bowl or the like by first forming an excavation having an interior profile roughly corresponding to the desired final interior profile of the structure. A large number of pins or pegs are driven into the bottom and side walls of the excavation, with the pegs being driven such that the outer end of each peg is at a predetermined location corresponding to a point on the desired interior profile of the structure. A cementitious material such as gunite or the like is then sprayed onto the side walls and bottom of the excavation, and the outer ends of the pegs are used as screeds for hand-forming the gunite to its desired final cross-sectional shape.
There are numerous drawbacks to the above-described method of forming an interior structure. For one, the method is extremely slow, time consuming and labor intensive. Additionally, even with great care and attention, tradesmen placing the pegs and forming the gunite using the pegs as screeds are necessarily limited by available tools and materials, and it is difficult, if not impossible, to form a structure having a ridge-free and ripple-free interior surface.
The present invention is designed to provide an apparatus and method for relatively quickly and efficiently forming an interior structure having a smooth and continuous interior surface.
In accordance with the method of the invention, an excavation is formed providing a bottom and one or more side walls extending upwardly therefrom. An interior forming assembly is provided, which has an inner end and a forming edge disposed towards its outer end. The forming assembly is placed into the excavation, and the inner end of the forming assembly is fixed relative to the excavation along a pivot axis substantially coincident with the center of the desired curved final interior surface of the structure. A wet cementitious material is applied to the side walls and bottom of the excavation, with the thickness of the material as applied being greater than the desired final thickness of the walls of the structure. The forming assembly is then pivoted about its pivot axis, whereby the forming edge of the forming assembly forms the cementitious material to its desired curved interior profile. The forming edge of the forming assembly preferably includes a surface for forming the cementitious material applied to the excavation side wall as well as that applied to the excavation bottom. The step of fixing the inner end of the forming assembly preferably comprises providing an axially extending member, securing the member at a first point toward the bottom of the excavation, and securing the member at a second point spaced above the bottom of the excavation. In this manner, when the axially extending member is secured, the member is substantially coincident with the center of the desired curved interior profile. The forming assembly is then mounted to the axially extending member for pivoting movement thereon. This method is advantageously employed when the forming assembly is pivoted about its entire range of movement about its pivot axis, so as to define a substantially circular interior shape to the cementitious material.
In accordance with another aspect of the invention, an apparatus is provided for forming a cementitious material to an arcuate interior profile, the material being applied to one or more side walls of an excavation. The apparatus comprises forming means having an inner end and a forming edge disposed towards its outer end. The forming means is adapted for placement into the excavation. Means is provided for fixing the inner end of the forming means relative to the excavation such that the forming means is pivotable about a pivot axis substantially coincident with the center of the desired final interior shape of the structure. The forming means is pivotable about its pivot axis such that the forming edge of the forming means acts to form the cementitious material on the side walls of the excavation to its desired cross-sectional profile during pivoting movement of the forming means about the pivot axis.